This invention relates in general to conduits for delivering fluids from one location to another. In particular, this invention relates to an improved method of manufacturing a pressure damper for use with such a fluid conduit for reducing or eliminating transient pulses of fluid pressure that may be generated in the fluid being delivered therethrough.
Most engines, such as internal combustion engines and diesel engines that are used in vehicles and other devices, are equipped with a system for delivering fuel from a source or reservoir to a plurality of combustion chambers provided within the engine. In most modern vehicular engines, this fuel delivery system is a fuel injection system, wherein fuel is supplied under pressure to and is selectively injected within each of the combustion chambers of the engine for subsequent combustion.
To accomplish this, a typical fuel injection system includes one or more fluid conduits (typically referred to as fuel rails) that transmit the fuel from the source to each of the combustion chambers of the engine. Each of the fuel rails is usually embodied as a hollow tube including an open end, a closed end, and a plurality of nodes located between the open and closed ends and that extend outwardly from the hollow tube. The open end of the fuel rail is adapted to communicate with the source of the fuel. The hollow tube is shaped such that each of the nodes is positioned directly adjacent to an inlet of an associated one of the combustion chambers of the engine. Each of the nodes usually terminates in a hollow cylindrical cup portion that is adapted to receive a fuel injector therein. The fuel injectors are typically embodied as solenoid controlled valves that are selectively opened and closed by an electronic controller for the engine. When opened, the fuel injectors permit the pressurized fuel to flow from the fuel rail into the associated combustion chamber. When closed, the fuel injectors prevent the pressurized fuel from flowing from the fuel rail into the associated combustion chamber. By carefully controlling the opening and closing of the fuel injectors, precisely determined amounts of the fuel can be injected under pressure from the fuel rail into each of the combustion chambers at precisely determined intervals.
Typically, the fuel rails are formed from a rigid material, such as a plastic or metallic material. Plastic material fuel rails can be formed by injection molding and other well known processes. However, the majority of fuel rails are manufactured from metallic materials. Typically, a metallic fuel rail is manufactured by initially providing a tubular body portion that is bent or otherwise deformed to a desired shape. Then, a plurality of openings are formed through the hollow body portion at the locations where it is desired to provide the above-mentioned nodes. A hollow node portion (typically having the cup portion already formed therein) is next positioned adjacent to each of the openings and is secured thereto, such as by brazing.
In fuel rails for most vehicular and other fuel injection systems, the various devices associated with the fuel system can cause transient pulses of fluid pressure to propagate throughout the fuel rails. These transient pressure pulses can undesirably cause varying amounts of the pressurized fuel to be injected from the fuel rail into the associated combustion chamber when the fuel injectors are opened. In addition, such transient pressure pulses can cause undesirable noise to be generated by the fuel delivery system. The transient pressure pulses can further result in false fuel pressure readings being taken by fuel pressure regulators, which may result in fuel being bypassed and returned to the fuel tank.
To address these problems, it is known to incorporate a pressure damper in a typical vehicular fuel delivery system. In one known pressure damper, a wall that forms a portion of a fuel supply line is formed from a flexible material. As pressure pulses occur within the fuel supply line, the flexible wall expands and contracts to dampen the magnitude of the pressure pulses. In another known pressure damper, a spring-loaded mechanism is provided within or connected to a portion of a fuel rail for the same purpose. In a further known pressure damper, a compliant member is provided within the fuel rail, again for the same purpose. Although known pressure dampers have been effective, it would be desirable to provide an improved method for manufacturing such a pressure damper that is simple and inexpensive in manufacture and construction.